Vehicles today use secondary batteries to power certain aspects of the vehicle operation. Different current demands are required by different controls, diagnostic equipment, etc., within a vehicle. Furthermore, certain data must be maintained for data collection or operation of the vehicle. A secondary battery is needed to maintain such recorded data or configuration information. A primary battery would be problematic in a vehicle in that because of the power demands, recharging is necessary.
Currently, there are separate devices that have a battery internally, which is used to keep the vehicle memory powered during removal of the main vehicle battery. Current devices only supply a secondary power via an internal battery to maintain vehicle memory and provide current measurement information by threshold indicators or readouts. The secondary power via an internal battery is usually also a secondary battery, but can be a primary battery depending on the load.
When a vehicle's secondary battery is drained, it can be either be at the end of its life span or the vehicle has drained the secondary battery without it being recharged. A faulty alternator may prevent the battery from being recharged, or the wiring from the alternator to the battery is faulty. Additionally, it may simply be a light left on while the vehicle is not in a recharging state. A parasitic drain in general is when an electrical device such as a vehicle is using the power from a battery, when the vehicle is not in a recharging state, e.g., when gas combustion of an engine in a vehicle powering the alternator is off.
In order to perform a parasitic drain test, one should make sure that the internal and external light emitting sources are in the off position, as that is a major drain on the battery. A general technique to test for the parasitic drain is to first remove the negative wire from the battery's negative electrode. As a general rule, when a circuit is complete or is about to be complete with the final connection, a user should only touch upon the grounded or negative electrode of an electrical power source in order to avoid the potential of shock. Grounding is usually established by connecting the negative electrode of the vehicle battery to the ground post, which connects to the body of the vehicle.
Then, a user attaches a test light between the negative battery electrode and negative battery post. Thereafter, the user must wait a certain duration for the vehicle to go into a sleep mode. If the test light is powered brightly, then there is something in the vehicle that is using too much power from the battery. Then, one must go to the fuse panel and remove the fuses to see what is the source of the power drain, thereby identifying the specific circuit that is draining the battery. Once the specific circuit is identified, then each specific device on the circuit must be checked, until the test lamp is dimly lit in order to ascertain that the battery drain is at an acceptable level. Such methods are harsh and are prone to errors and problems. The testing itself may cause further drain and is only helpful when the battery is fully recharged.
There are devices similar that sense the vehicle's current draw when the vehicle's battery is disconnected. Usually the internal battery of the device has to be high current draw etc. and is a wear item. There is also a need to log current draw (parasitic load) over a long period of time (up to an hour or more) as it takes that long for a vehicle to shut down to a low current state. There is a further need to address the problem of depleting internal batteries because power is supplied by the battery charger.
Accordingly, it is desirable to provide an apparatus and technique for correcting the problem of depleting an internal battery and to more accurately monitor the current information as it relates to the battery drain and starter current.